Windows 10 Troubleshooting 0xc0000021A


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Hi all,

I've had quite a hard time trying to troubleshoot error code 0xc0000021A upon boot, resulting in a blue screen.
So far I've only managed to boot up the machine by disabling driver signature enforcement using the advanced startup recovery options, any others won't work (even safe mode).
This leaves my machine vulnerable and unusable for some applications, so I'm looking to fix this issue.

The issue popped up recently, after installing several programs associated to graphics and games.
I've tried uninstalling (and re-installing afterwards) all of those components trying to fix the issue, without any luck.

I've ran Malwarebytes scans, Windows Defender scans, Kaspersky's TDSSKiller and some other ones - all of them with 0 infections found.

Other options in the advanced startup recovery menu don't seem to help either:
- System Restore isn't available as there are no restore points to before the point when the problem occurred.
- Windows Startup Repair can't manage to fix the issue.
- System Image Recovery isn't available as there are no recent images.

chkdsk finds no errors or bad sectors.

sfc failed several times after i managed to boot up the machine. Until i ran it from CMD in advanced startup recovery options as described here, then it said it ran succesfully once - however when running it again there are remaining issues with C:\WINDOWS\System32\aepic.dll in the CSB log:
Hashes for file member \??\C:\WINDOWS\System32\aepic.dll do not match actual file [l:9]'aepic.dll'
I don't want to grab any dll i could use to replace it with from the net, since I don't know any reliable sources for these kind of DLLs.

Also, Windows 10 is up to date.

Is there anyone who can help me out troubleshooting this issue?
I don't know where to look anymore and re-installing the machine completely isn't an option at the moment.
Any hint or direction to look in would be appreciated, thanks in advance!

Kind regards,
Kevin
 
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Regedit32

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Hi Xaero91,

Welcome to the Forum.

From your post it appears you have all ready tried a few standard options to attempt to resolve your issue.

Given the lack of success there I would suggest your simplest option at this point in time would be to download the Windows 10 ISO matching your current setup, and then running an in-place upgrade, which effectively installs Windows over the top of itself.

First things first though. How to get the ISO:

Go here: https://www.microsoft.com/en-us/software-download/windows10

Select the Download Tool which will download a 17.4 MB file to your computer.

Sample image

mct.png


Once downloaded, go to the download and run it. You see the following screens in this order. Do as in the sample images posted:

mct1.png


mct2.png


mct3.png


mct4.png


mct5.png


A 4.42 GB iso image will download. You will eventually see this screen:

mct6.png


It will then take a few seconds to clean up and close and your download will be on your Desktop or wherever you chose to save it to.

Report back when you have downloaded the ISO and I'll post some instructions on doing an in-place upgrade if you need help with that.

Regards,

Regedit32
 
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Hi Regedit32,

Thanks for your reply. So this solutions would keep all programs and files in place, only overwrite Windows files? Also, what is the risk compared to the chance it will actually solve the issue (as we didn't get to the actual cause)?

I've already done the above in order to try some fixes yesterday.
The only difference is, I've got it installed as a USB Drive:
upload_2017-3-18_15-3-10.png


I guess this will do the exact same.

Cheers,
Kevin
 

Regedit32

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If it's on your Desktop, you can right-click and select Mount then when the window opens. click the Setup.

At some point there will be a screen asking you to choose between saving files and settings, or a clean install.

Obviously, you will want the Save files and settings option.

Some third party applications may need to be reinstalled afterwards despite that though.

You can alternatively make use of the Install.WIM file found inside the mounted folder, to run a DISM Restore-Health command which may be able to resolve that aepic.dll issue you mentioned by replacing what may be a corrupt version with a clean one from the Install Windows Image.
 
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Alright thanks for the info!
I will try the DISM command first before proceeding to do a reinstall.

Let's see where this goes, wish me luck :)
 

Regedit32

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OK if you plan on taking that route first, then some things you need to do to prevent a stuff up per se.
  • First right-click on the ISO you downloaded and select Mount
  • Open the Sources folder and scroll and copy the Install.esd file to your Desktop [this is a 3.9 GB file]
  • Now right-click on Start and select Command Prompt (Admin)
  • Click Yes when the User Account Control seeks confirmation
  • In the Command Prompt: Administrator window type or copy & paste the following:

    Code:
    dism /get-wiminfo /wimfile:"%userprofile%\desktop\Install.esd"

    Press Enter key to execute.

    This will tell you the content of the Install.esd file, and you want to note the index number for the OS you intend to install. I'm using Windows 10 Home on this computer so for me the Index number is 2 as can be seen in the sample image below.

    Sample image

    dism.png

  • Now change directory to the Desktop by typing cd %userprofile%\desktop then pressing Enter key
  • Type CLS then press Enter key to clear screen
  • Now you want to convert the ESD to a WIM file. To do this type or copy & paste the following command:

    Code:
    dism /export-image /SourceImageFile:install.esd /SourceIndex:2 /DestinationImageFile:install.wim /Compress:max /CheckIntegrity

    Note: Remember to enter the correct Index number in above command to reflect your OS. As this computer is using Windows 10 Home, for me the SourceIndex is 2

    Press Enter key to execute. The conversion process will take a few minutes. Be patient :mad::rolleyes:

    Sample image

    dism1.png

  • OK now that 15 minutes of your life just passed away, switch to your Desktop and delete the copied Installed.esd file as you should now have a nice new Install.wim file sitting on the Desktop taking up 3.81 GB of space.
  • Return to your Command Prompt: Administrator console and type CLS then press Enter key to clear screen. Make sure you are still at your Desktop prompt.
  • Type or Copy & paste the following command:

    Code:
    Dism /mount-wim /wimFile:%USERPROFILE%\Desktop\install.wim /index:1 /MountDir:%USERPROFILE%\Desktop\mount

    Press Enter key to execute.

    Note: You will notice in this example my index number has changed from 2 to 1. This is because the new Install.wim file now only contains the OS (in my case Windows 10 Home) so there are no other index numbers to be concerned with.

  • Next type or copy & paste the following command:

    Code:
    Dism /Online /Cleanup-Image /CheckHealth

    Press Enter key to execute

  • Next type or copy & paste the following command:

    Code:
    Dism /Online /Cleanup-Image /RestoreHealth /Source:%USERPROFILE%\Desktop\mount\windows /LimitAccess

    Press Enter key to execute

  • Next type or copy & paste the following command:

    Code:
    Dism /unmount-wim /Mountdir:%USERPROFILE%\Desktop\mount /discard

    Press Enter key to execute

  • Finally, type or copy & paste the following:

    Code:
    SFC /SCANNOW

    Press Enter key to execute

Remember all this assumes you had all ready run an SFC scan earlier which you clearly did as it marked an error with a particular dll file according to your opening post. All going well Windows can resolve that making use of your clean copy of Install.wim

At this point if you like you could now delete the Install.wim file to save disk space. You can always recreate it from the Install.esd still in your original downloaded ISO file.


Hope it works out for you.

Regards,

Regedit32


 
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Hi Regedit32,

Thanks a lot for your detailed description.

I've executed all steps and commands as described successfully, but i keep running into the same issue.
When executing sfc /scannow at the end, it finds the error regarding the aepic.dll file.
It tells me to restart to finish the fix, but i'm forced to click shift+Restart so i can go into startup options and choose to disable driver signature enforcement since it will run into the BSOD otherwise.
I think this might prevent the on-boot process from sfc from actually applying the fix.

I could try and do the same when from booting the Windows 10 USB drive into CMD again, see if that works out.

Anyway i'm starting to consider doing a 'Refresh'/'Reset' though since it's starting to become a blocking issue by now.

Thanks again for your help.

Cheers,
Kevin
 

Regedit32

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If the SFC and DISM commands are not resolving your issue, then there is still the option of an in-place upgrade.

Right-click the ISO and mount, then run the Setup you see.

As you go through the screens you'll get a chance to save files and settings.
 
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When running the sfc command from the USB drive, it says it found errors and fixed them successfully, but when running it again it showd the exact same message and log.
So I'm guessing it can't fix the issue.

I'll try an in place upgrade with the ISO file then, after i verified the RAM isn't faulty.

Thanks for the info!

Cheers,
Kevin
 

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